1. Field of the Invention
The present invention relates to an adhesive composition having excellent adhesive durability and reworkability.
2. Description of the Prior Art
In general, a liquid crystal display (LCD) is composed of polarizing plates and a liquid crystal cell containing liquid crystals. Several optical films (retardation plate, viewing angle expansion film, brightness enhancement film, and the like) are used to improve the display quality of the LCD.
These polarizing plates and optical films are bonded to the liquid crystal cell by using an adhesive. For the adhesive, an acryl-based adhesive containing an acryl-based polymer having excellent adhesiveness and transparency as a base material is typically used. The cross-linkage of the acryl-based adhesive employs the linkage of a cross-linking agent with a functional monomer of the acryl-based polymer.
An adhesive composition containing a silane-based Compound having an epoxy group has been known as an adhesive [Japanese Patent Publication No. Hei 4-223403]. However, the above-mentioned adhesive cannot retain such an adhesive strength as required in a real usage environment. Moreover, the adhesive strength of the adhesive may excessively increase under high temperature and humidity conditions or the adhesive may be remained on a substrate when being peeled again.
In addition, an adhesive composition containing a silane-based compound having a cyano acetyl group [Korean Patent No. 840114] and an adhesive composition containing a silane-based compound having an acetoacetyl group [Korean Patent No. 6714000] have been proposed. The above-mentioned adhesives have excellent reworkability since the adhesive strength of the adhesives does not excessively increase under high temperature and humidity conditions and thus the adhesives are not remained on a substrate when being peeled again. However, the initial adhesive strength of the adhesives is relatively low and the adhesive durability of the adhesives under strict conditions (high temperature or high temperature and humidity) becomes deteriorated.